The present invention relates to a method for determining a mixing ratio of a number of n organic miscible components in a mixture thereof. The present invention also relates to a method of using an inorganic marker.
Commercially available multicomponent mixtures, for example mousses, foams, sealants and adhesives, once prepared or applied, frequently make it impossible to determine the original mixing ratios between the components. This compromises the qualitative policing of the manufacturing operation for multicomponent mixtures and hinders any attempt to reconstruct the causes of process discrepancies. As a result, mixtures manufactured are incapable of meeting the functional expectations.
Proceeding from this prior art, the present invention addresses the problem of devising a method for determining a mixing ratio of n organic miscible components in a mixture thereof that is technically quick and easy to implement and enables a quantitative analysis of the component quantities originally used for the mixture. The present invention also addresses the problem of devising a use for an inorganic marker.
The problem is solved by a method for determining a mixing ratio A of n organic miscible components in a mixture thereof, comprising the steps of: i) providing n components in predefined amounts, where n is an integer ≥2, ii) mixing respectively one inorganic marker with each one of components respectively in a predefined mixing ratio of the particular inorganic marker to the particular component, wherein at least one component is mixed with one inorganic marker, and wherein the inorganic markers differ in chemical nature, iii) preparing a mixture of the components, iv) performing an analysis to quantitatively determine the amounts of the inorganic markers, and v) determining the mixing ratio A of the n components from the ascertained amounts of the inorganic markers via the particular predefined mixing ratios of the particular inorganic marker to the particular component.
The method of the present invention is applied to mixtures of different organic components which, more particularly, are homogeneously miscible with one another, i.e., form an essentially monophasic mixture. Organic components for the purposes of the present invention are chemical materials or compositions of matter that are or contain functional, active or reactive compounds based essentially on hydrocarbon compounds. Compositions of matter, in addition to hydrocarbon-based compounds, may also contain other organic or inorganic additions such as fillers, pigments, viscosity-regulating substances, antioxidants and the like. These additions do not influence the functionality, activity and/or reactivity of the hydrocarbon-based compounds. The components may further also contain functional additives, for example catalysts. Organic compounds for the purposes of the present invention come with preference from among manufactured polymers or their starting compounds.
The number n of organic miscible components provided according to the present invention is discretional provided n is an integer not less than 2. Each component is mixed with a specific inorganic marker. An inorganic marker is a nonvolatile inorganic compound which is inert with respect to the components and the processing of the components and which does not have a natural origin in the components. A marker is thus an inorganic compound which is typically not present as an additive in the components. Since customary additives are often added to organic components in varying amounts (for example, in the case of viscosity-regulating substances) or merely for technical reasons, as is the case for example with fillers, or alternatively different components contain the same additives (for example the same fillers or pigments), traditionally added additives are not useful as markers for the purposes of the invention. It is not absolutely necessary for all components to be provided a marker; on the contrary, at least those components whose mixing ratio A is to be determined are provided markers. In one embodiment, all components may be provided a marker, so the mixing ratio of any one component to any other component as well as the overall mixing ratio of all components can be determined. In this case, n is the number of markers as well as the number of components.
The particular markers which are mixed with the particular components differ in chemical nature, so their quantities can be quantitatively determined independently of each other. This is a requirement for the later step of the analysis. Once the particular inorganic marker or markers have been mixed with respectively one of the components in respectively a predefined mixing ratio of particular marker to particular component, the components are subsequently processed to afford a mixture. This may be done using commercially available mixing devices, for example a dynamic mixer. The mixture may also contain components that do not include any markers, examples being auxiliary materials, such as solvents and other additives. The amounts thereof do not enter into the A mixing ratio to be determined. The mixture accordingly comprises a homogeneous distribution of all the components and additives added and also of the markers.
This is followed, for example after taking a sample of the mixture or after further processing the mixture, for example after applying the mixture, by a step of performing an analysis to quantitatively determine the amounts of the inorganic markers. The mixture is thus analyzed for ascertaining the amounts of the particular markers. When the marker undergoes a reaction during analysis, the analytical technique is chosen such that the stoichiometry of this reaction is unambiguously known, so the original amount of marker can be deduced.
As a result of the original mixing ratio of any one marker to the particular component mixed with the marker being known, i.e., predefined “marker to component” mixing ratios being present in each case, and by virtue of the fact that the marker is inert and nonvolatile, it is possible to take the corresponding ascertained quantities of marker and deduce therefrom the original quantity of the particular component, from which the mixing ratio A of the components is derivable.
The method of the present invention requires the addition of quantitatively analyzable markers to customarily used components and also the quantitative determination of the markers in a mixture of the components. The technical and time requirements of the method according to the present invention are thus low. The method can be carried out, after sampling, concurrently with the manufacture of products out of the component mixture, making it possible to adjust and re-adjust the manufacturing process and ensure a qualitatively high standard for the products obtained. The method of the present invention provides a simple way to police the mixing ratios of multicomponent systems to assure the functionality and quality of these systems.
In an advantageous development of the method according to the present invention, n-1 components are mixed with respectively one inorganic marker. This means that there are solely n components, all but one being mixed with a marker each. Even though one component does not contain a marker, the amount originally used thereof, and hence the mixing ratio A, is ascertainable from the difference of the ascertained amounts of components having markers via the analyzed “marker to component” mixing ratios. This saves the cost for the marker and reduces the analytical burden while providing equivalent information about the mixing ratio A.
It is advantageous here not to provide a marker to that component which, volumetrically, accounts for the largest share of the mixture of the components. This has been determined to be advantageous for measurement accuracy.
Owing to their high chemical inertness and non-volatility, the inorganic marker is preferably selected from metal oxides and/or metal sulfides. One marker may be used per component, but it is also possible to employ two or more different markers per component, in which case the markers of these components are likewise each chemically different than the markers of the other components.
Very useful markers include oxides or sulfides of the elements copper (Cu), zinc (Zn), iron (Fe), nickel (Ni) and manganese (Mn). Zinc sulfide (ZnS) is a particularly preferred inorganic marker because the quantitative analysis of ZnS is simple to perform and leads to low error rates. ZnS is further sufficiently available in the industrial context and is not toxic and does not cause a health concern.
To save costs as well as substantially reduce impairments to the components regarding their chemical, physical and mechanical properties, another advantageous development is characterized in that a proportion of inorganic marker, based on a combined weight of the respective inorganic marker and the particular component whereto the inorganic marker is added, is less than 5 wt %, preferably from 0.5 to 2 wt %.
In a further embodiment, the present invention provides the step of performing an analysis comprises an ash determination for the mixture as per DIN EN ISO 1172:1998-12 and/or an acid digestion of the mixture. An ash determination is done at temperatures where the functional, active or reactive, essentially hydrocarbon-based compounds of the organic components burn to leave solely inorganic products behind as an ash. Calcination is done to constant weight, so the mixing ratio of the components can be directly deduced from the residue. An acid digestion may be done using aqua regia in particular. This will cause all customary inorganic markers to dissolve. A qualitative analysis of the markers may then be effected by suitable spectroscopic methods provided the spectroscopic method does distinguish between the markers qualitatively. It is thereby possible to perform a precise qualitative analysis of each and every marker even in multicomponent systems having more than two components and more than one marker.
In a further embodiment, the present invention provides that the step of performing the analysis comprises a quantitative determination of the inorganic marker by inductively coupled plasma optical emission spectrometry (ICP-OES), atomic absorption spectroscopy (AAS) or atomic emission spectroscopy (OES). ICP-OES, also known as ICP-AES or ICP plasma spectroscopy, is an optical emission spectroscopy featuring inductively coupled plasma (ICP) as excitation source, which offers ease of handling, high sensitivity and precision and also a relative freedom from interferences. It enables qualitative and quantitative analysis of the marker at one and the same time, so every component can be assigned a corresponding amount of marker.
It is further advantageous for the organic miscible component to be selected from thermoplastics, thermosets, elastomers and their starting compounds, e.g., the monomers used. These organic compounds are extensively used in multicomponent systems and functional products, so the determination of the mixing ratio of their starting components is very germane. It is preferable for these organic components to include particularly polyurethanes, epoxides, polyacrylates, polyamides, polyolefins and mixtures thereof.
The method of the present invention is further applied with advantage to a mixture that is an adhesive, a sealant or a foam. Particularly these homogeneous mixtures have a high level of functionality, the quality of which by determining the mixing ratio A is of essential significance.
The present invention likewise provides the method of using an inorganic marker for determining a mixing ratio of components in multicomponent mixtures such as foam, adhesive and sealant materials. ZnS is particularly useful as the marker.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.